KR20010099645A - Method for improving mobile radiocommunication system performances using a power control algorithm - Google Patents

Abstract

A method for improving performances of a mobile radiocommunication system using a power control algorithm for controlling a transmit power according to a transmission quality target value, and an adjustment algorithm for adjusting said transmission quality target value according to transmission requirements, said method including, upon the occurrence of a change in said transmission requirements, bypassing said adjustment algorithm, by applying a corresponding change to said transmission quality targetvalue, so as to adjust it in an anticipated way.

Description

[0001] METHOD FOR IMPROVING MOBILE RADIOCOMMUNICATION SYSTEM PERFORMANCE [0002] USING A POWER CONTROL ALGORITHM [0003]

As is well known, a CDMA system has two types of power control technologies, so-called open-loop power control techniques and so-called closed-loop power control techniques CLPC "). With these power control techniques, for example, the uplink transmission direction, that is, the direction from the MS (" Moble Station ") to the BTS (" Base Transceiver Station ") can be considered. In open-loop power control, the MS transmit power is controlled based on the power received by the MS from the BTS. In the CLPC, the MS transmit power is controlled based on the transmission quality of the link between the MS and the BTS, as measured by the BTS.

The transmission quality of the link between the MS and the BTS correlates to the ratio of the received signal power to the interference power - also called signal-to-interference (SIR). If the SIR of the MS is low, or equivalently, the power of the other MS is much higher than its MS power, then the performance drops dramatically. The CLPC algorithm can keep the SIR of each user as close to the target SIR as possible.

The principle of the CLPC algorithm is that the BTS periodically measures the SIR of a signal received from each MS and transmits the measured SIR to the target SIR ( ). If the measured SIR is lower than the target SIR, the BTS sends a power control command to the MS and the MS increases its transmit power. Otherwise, the BTS sends a power control command to the MS, which reduces its transmit power.

The target SIR is an important parameter in this system. In fact, if the target SIR value is set to a value higher than necessary, unnecessary interference level is given to the system, and unnecessary system performance is degraded. On the other hand, if the target SIR value is set to a value less than necessary, the performance of the on-going communication is deteriorated.

The target SIR is generally selected as a function of the quality required for the service and is adjusted by the so-called outer loop algorithm (also opposed to what is referred to as the inner loop algorithm). The principle of the outer loop algorithm is to regularly measure the quality of service (generally indicated by the bit error rate BER or frame error rate FER for the voice service, or the block error rate BLER for the data packet service) Compare to the required quality of service. If the measured quality is below the required quality of service, the target SIR increases. Otherwise, the target SIR decreases.

Contrary to the inner loop algorithm which needs to speed up to track the SIR variation as closely as possible, the outer loop algorithm needs to be slowed because its quality needs to be averaged over a certain period to have a reliable measurement have. Typically, for example, in a third generation system such as UMTS (" Universal Mobile Telecommunications System "), the SIR of the received signal is determined and compared to the target SIR for each slot in the frame, A slot that is the basic unit of time in the data unit or frame being transmitted, a frame duration that is typically 10 ms, and a slot duration that is 1/15 of the frame duration).

However, this low speed process can cause serious problems, especially when the so-called compression mode is used.

To make it possible for a user equipment (UE) to make measurements on a frequency different from its downlink transmission frequency, a downlink compression mode was introduced in UMTS. This basically involves stopping the downlink transmission for a certain amount of time (transmission gap). The concurrent uplink and downlink compression modes may also be used when the measured frequency is close to the uplink transmission frequency.

Since the instantaneous bit rate will be increased during the compression frame (by either increasing the coding rate or by decreasing the spreading factor), the target SIR also needs to be increased approximately by the same ratio

Also, closed-loop power control during the transmission gap for the downlink and uplink. Since it is no longer active, its performance is significantly degraded, mainly during compression and recovery frames (frames immediately following the compressed frame). That drop can reach several decibels. To maintain the same quality of service as the normal (or non-compressed) mode, this effect will also need to be compensated by increasing the target SIR during these frames.

However, the outer-loop power control algorithm is a slow process and several frames will probably be needed before changing the target SIR accordingly. Therefore, this process is too slow to easily increase the target SIR in the compressed frame and the recovered frame as needed. Also, the target SIR is at risk of being increased even after compression frames and recovery frames that are not needed.

Therefore, in compression mode, faster processing than a typical outer-loop algorithm is required to avoid its performance degradation.

More generally,

- change from non-compressed mode to compressed mode, or vice versa,

- changes in required services (in particular, changes in transmission speed),

- changes in transmission rate for a given required service (eg, data packet service)

- Changes in environmental conditions (moving speed, radio propagation conditions),

-... Etc

In the case of any change requiring a transmission involving a higher speed than a typical outer-loop algorithm, a process is required.

Therefore, generally, in order to improve the performance, more effective power control is required.

Accordingly, it is an object of the present invention to provide a method and apparatus for improving performance of a mobile wireless communication system, using a power control algorithm for controlling transmission power according to a transmission quality target value and an adjustment algorithm for adjusting the transmission quality target value according to a transmission request Wherein the method includes bypassing the power control algorithm by applying the change to the transmit power when a change in the transmit request occurs.

According to another object of the present invention, the method further comprises bypassing the power control algorithm by applying the change to the transmit power in the event of a change in the transmit request.

In this way, its performance is also improved by enabling its transmit power to be as close as possible to the new transmit quality target value.

According to another object of the present invention, the change in the transmission request includes a change from the non-compressed mode to the compressed mode, and the change may be applied before the compressed frame, including the increase of the transmission quality target value.

According to another object of the present invention, the change in the transmission request includes a change from a non-compression mode to a compression mode, the change including an increase in the transmission quality target value, Lt; / RTI >

According to a further object of the invention, the change in the transmission request comprises a change from a compressed mode to a non-compressed mode, the change comprising a decrease in the transmission quality target value, have.

According to another object of the present invention, the change in the transmission request includes a change from a compressed mode to a non-compressed mode, the change includes an increase in the transmission quality target value, And may be applied during one or more recovery frames following ending.

According to another object of the present invention, the transmission quality is represented by a signal-to-noise ratio.

According to another object of the present invention, the mobile radio communication system is a CDMA type system.

According to another object of the present invention, the power control is performed in the uplink transmission direction of the mobile radio communication system.

According to another object of the present invention, the power control is performed in the downlink transmission direction of the mobile radio communication system.

Another object of the present invention is a mobile wireless communication system including at least a transmitting entity and a receiving entity for carrying out such a method, and when a change in the transfer request occurs, a first entity of the entities, Means are provided for bypassing the adjustment algorithm by applying it to a transmission quality target value and adjusting it in an expected manner.

According to another object of the present invention, the first entity is provided with means for determining and / or updating the corresponding change.

According to another object of the invention, a second entity of the entities is provided with means for signaling the previous value needed to determine and / or update the corresponding change to the first entity.

According to another object of the present invention, a second entity of the entities is provided with means for signaling the corresponding change to the first entity.

According to another object of the invention, a first entity of the entities is provided with means for signaling the first entity of the occurrence of a change in the transfer request.

According to another object of the present invention, a second entity of the entities is provided with means for signaling the change to the first entity, together with signaling of the occurrence of a change in the transfer request.

According to another object of the present invention, means for recording the corresponding attitude is provided in any one of the two entities.

According to another object of the invention, one of the two entities is a mobile wireless communication network entity.

According to another object of the invention, one of the two entities is a mobile station.

It is another object of the present invention to provide a method and apparatus for performing such a method in the uplink transmission direction,

Means for bypassing the adjustment algorithm and adjusting it in an expected manner by providing a corresponding change in the transmission quality target value in order to adjust it in an expected manner when a change in the transmission request occurs;

Lt; RTI ID = 0.0 > wireless < / RTI >

According to another object of the invention, the mobile wireless communication network entity comprises:

And means for bypassing the power control algorithm and adjusting it in an expected manner by applying the change to the transmit power when a change in the transmit request occurs.

Another object of the present invention is a mobile station including means for bypassing the adjustment algorithm and adjusting it in an expected manner by applying the change to the transmission quality target value when a change in the transmission request occurs.

According to another object of the present invention, in order to perform this method in the downlink transmission direction,

And means for bypassing the power control algorithm and adjusting it in an expected manner by applying the change to the transmit power when a change in the transmit request occurs.

It is another object of the present invention to provide a method for performing such a method in the downlink transmission direction,

And a mobile wireless communication network entity including means for signaling the corresponding change to the mobile station.

According to another object of the present invention, in order to perform this method in the downlink transmission direction,

- means for signaling the mobile station of the occurrence of a change in the transmission request

.

It is another object of the present invention to provide a method for performing such a method in the downlink transmission direction,

- means for signaling the mobile station to signal a change in the transmission request,

.

According to a further object of the present invention, the change in the transmission request comprises a change from a non-compressed mode to a compressed mode and / or a change from a compressed mode to a non-compressed mode, Signaling. ≪ / RTI >

According to another object of the present invention, the change in the transmission request includes a change from a non-compressed mode to a compressed mode and / or a change from a compressed mode to a non-compressed mode, Lt; RTI ID = 0.0 > a < / RTI >

According to another object of the present invention, the signaling is performed for each compressed frame.

According to another object of the present invention, when a compressed frame occurs periodically, the signaling is performed once for every compressed frame of a prescribed period.

These and other objects of the present invention will become more apparent from the following description with reference to the accompanying drawings.

The present invention relates generally to mobile wireless communication systems.

The present invention relates in particular to power control techniques used in systems for improving performance (in terms of quality of service such as capacity ...).

The present invention is particularly applicable to a CDMA (Code Division Multiple Access) type mobile radio communication system. In particular, the present invention is applicable to UMTS (" Universal Mobile Telecommunication System ").

1 is a diagram of a diagram intended to illustrate the different steps of a current (uplink or downlink) power control process;

2 is a diagrammatic diagram intended to illustrate other steps of a modified power control process to include a method (in an uplink or downlink) according to the present invention.

3 is a diagrammatical diagram intended to illustrate examples of means that can be used for mobile stations and mobile wireless communications network entities to perform the method according to the present invention for uplink power control.

4 is a diagram illustrating an example of a means that may be used by a mobile radio communications network entity and a mobile station to perform a method in accordance with the present invention for downlink power control.

1, the current power control process includes an inner loop algorithm (also referred to herein as an adjustment algorithm) 1 and an outer loop algorithm (also referred to herein as an adjustment algorithm) 2.

The inner loop algorithm (1) includes the following steps,

- in step 10, the receiving entity measures the SIR received and averaged over period T,

- in step 11, the receiving entity sends this SIR to the target SIR, ≪ / RTI >

-SIR> , Then in step 12 the receiving entity sends a " down " power control command to the transmitting entity, dB - Is the size of the power control step of the algorithm -

-SIR < , Then in step 13 the receiving entity sends an " up " power control command to the transmitting entity, dB.

As shown in loop 14, this process is repeated periodically.

The outer loop algorithm (2) includes the following steps.

- in step 15, (E. G., BER), &lt; / RTI &gt;

- in step 16, the receiving entity compares this measured BER to a target BER (indicating the required quality of service)

-BER> , Then in step 17 Lt; / RTI &gt;

-BER < , Then in step 18 .

As shown in loop 19, this process is repeated periodically.

A variation of the power control process to include the method according to the present invention will be disclosed as follows. However, it should be noted that this example is not limiting, and the present invention is also applicable to other examples of algorithms.

In the example of Fig. 2 (the same reference numerals being used in Fig. 1), a new step 20 is introduced. In this step 20, it is determined whether or not a change has occurred in the transfer request.

If such a change has not occurred, the outer loop algorithm 2 is performed as in FIG.

If such a change has taken place, in order to adjust it in an expected manner to improve performance, Depending on the manner in which it is applied to the value, a new step 21 is performed.

In addition, if such a change has not occurred in the example of FIG. 2, the inner loop algorithm is performed as in FIG. If such a change has occurred, a new step 22 is performed, depending on how the change is applied to the transmit power, to improve performance by controlling it in an expected manner.

Such a corresponding change corresponding to a change in the transfer request may have a predetermined value that can be determined in any manner.

For example, the values may appear as system parameters and thus be determined by the operator of the system. Further, the values can be predetermined, in particular, by simulation. In any case, the values can be updated during operation. The values may be determined, for example, by averaging, based on previously obtained values during operation. In any case, the predetermined value of the obtention mode should take into account all factors or combinations of such factors that are likely to affect the change.

In addition, the values may be known to be used locally at any one of the two entities (the transmitting entity and the receiving entity) involved in the power control process, and the other entity of the entities, Signaling can be done that it will be used for this entity.

In addition, the values may be determined and / or updated at any one of the two entities based on statistics for previously obtained values, and may be locally available to the entity, Signaling is done to this entity by the entity.

In addition, the values may be recorded in any one of the entities and recovered as needed.

In addition, the occurrence of a change in the transfer request is locally known by the entity that is responsible for applying the change, or signaling is made to this latter entity by another entity of the entities.

Thus, all possibilities can be considered. Accordingly, it is to be understood that the examples given in this description are illustrative only and do not limit the nature of the invention.

3 is a diagram of a multi-annagram intended to illustrate an example of a mobile radio communication network entity 40, and means that may be used in the mobile station 41, for carrying out the method according to the present invention for uplink power control.

A mobile radio communications network entity (e. G., A base station controller), such as a BTS (or Node B in UMTS) for a " Base Transceiver Station " and / or a BSC 40) is configured to perform the method in the uplink transmission direction (in addition to other typical means not mentioned in the present invention)

- means (42) for bypassing the adjustment algorithm and adjusting it in an anticipated manner by applying the change to the benefit transmission quality target value to adjust it in an expected manner, when a change in the transmission request occurs,

. &Lt; / RTI &gt;

The mobile wireless communications network entity 40 may also be configured to perform the method in the uplink transmission direction (in addition to other typical means not mentioned in the present invention)

Means (42) for bypassing the power control algorithm and adjusting it in an expected manner by applying a corresponding change in the transmit power to control it in a predicted manner when a change in the transmit request occurs,

. &Lt; / RTI &gt;

Such a corresponding change corresponding to a change in the transfer request may have a predetermined value that can be determined, for example, according to any of the possibilities described above.

In any case, the mobile wireless communication network entity 40 may, for example,

- means (42 ') for recording said change;

. &Lt; / RTI &gt;

The mobile station 41 (or a User Equipment UE in UMTS) is responsible for performing the above method in the uplink transmission direction (in addition to other typical means not mentioned in the present invention)

Means (43) for signaling the occurrence of a change in a transmission request to a mobile wireless communication network entity,

. &Lt; / RTI &gt;

FIG. 4 is a diagram intended to illustrate examples of means that may be used for mobile radio network entity 45 and mobile station 46 to perform the method according to the present invention for downlink power control.

The mobile station 46 (or User Equipment in UMTS) is configured to perform the method in the downlink transmission direction (in addition to other typical means not mentioned in the present invention)

Means (48) for bypassing the adjustment algorithm and adjusting it in an expected manner, by applying the change to the transmission quality target value if a change in the transmission request occurs,

. &Lt; / RTI &gt;

The mobile station 46 may also be configured to perform the method in the downlink transmission direction (in addition to other typical means not mentioned in the present invention)

Means 48 for bypassing the power control algorithm by applying the change to the transmit power and adjusting it in an expected manner;

. &Lt; / RTI &gt;

Such a corresponding change corresponding to a change in the transfer request may have a predetermined value that can be determined, for example, according to any of the above-mentioned possibilities.

In one embodiment, the mobile station 46

- means (48 ') for recording said change;

. &Lt; / RTI &gt;

In another embodiment, a movement, such as a BTS (or RNC for " Radio Network Controller " in UMTS) for the BTS (or Node B in UMTS) and / or & The wireless communication network entity 45 may be configured to perform the method in the uplink transmission direction (in addition to other typical means not mentioned in the present invention)

- signal means (47) for signaling said change to the mobile station (46)

. &Lt; / RTI &gt;

In addition, the mobile wireless communication network entity 45

And signal means (47) for signaling the mobile station of the occurrence of a change in the transmission request.

Advantageously, the mobile wireless communications network entity 45

And signaling means 47 for signaling said change to said mobile station 46, together with signaling the occurrence of a change in the transfer request.

The invention may be applied to any one of the occurrences of a change in a transmission request, for example any one of the above-mentioned cases, or to any combination of these plurality of cases.

However, as will now be described in detail, the present invention relates in particular to the use of a compressed mode.

In order to keep the signaling as low as possible, the target SIR increases due to the increased instantaneous bit rate, the target SIR increases due to the degraded performance in the compressed frame, and can be distinguished as shown in the following equation.

Where R is the instantaneous total bit rate before and after the compressed frame, Is the instantaneous total bit rate during the compressed frame.

The bit rate change will be known by the UE and additional target SIR due to degraded performance during the compressed frame can be signaled. If this change is signaled with another compressed mode parameter (transmission gap length, periodicity, ...), the signal overhead may be lowered. For example, 2 bits Lt; RTI ID = 0.0 &gt; of: &lt; / RTI &gt;

-00: 0dB

-01: 0.5 dB

-10: 1dB

-11: 2dB

Alternatively, Can be directly signaled, but a larger number of bits will be needed.

The UE may send a target SIR immediately before the compressed frame (or just after the transmission gap of the compressed frame) And the target SIR immediately after the compressed frame should be decreased by the same value. This target SIR change is in addition to the conventional downlink outer-loop algorithm that has to be considered. The UE may simultaneously increase its transmit power by the same amount prior to the compressed frame and reduce it immediately after the compressed frame so that the received SIR for the downlink becomes as close as possible to this new target SIR.

Also, when at least the transmission gap is behind the compressed frame, the performance in the recovery frame may also be degraded due to power control disturbance due to the transmission gap. Therefore, it would also be desirable to increase the target SIR in the recovery frame and signal this target SIR to the UE. As another method, the same value as that of the compressed frame ( ) Can be used to reduce the required signal.

In addition, the signaling can be done for each compressed frame.

Alternatively, if compressed frames occur periodically, the signaling may be done once for all compressed frames of a defined period, to reduce the required signaling.

Claims (31)

A method for improving performance of a mobile wireless communication system using a power control algorithm for controlling transmission power according to a transmission quality target value and an adjustment algorithm for adjusting the transmission quality target value according to a transmission request, And bypassing the adjustment algorithm by applying the change to the transmission quality target value if a change in the transmission request occurs, adjusting it in an expected manner. 2. The method of claim 1 further comprising bypassing the power control algorithm and controlling it in an expected manner by applying the change to the transmit power when a change in the transmit request occurs, &Lt; / RTI &gt; 3. The method of claim 1 or 2, wherein the change in the transmission request comprises a change from a non-compressed mode to a compressed mode, the change comprising an increase in the transmission quality target value to be applied before the compressed frame A method for improving performance of a mobile wireless communication system. 3. The method of claim 1 or 2, wherein the change in the transmission request comprises a change from a non-compressed mode to a compressed mode, The method comprising the steps of: a. 5. The method of any one of claims 1 to 4, wherein the change in the transmission request comprises a change from a compressed mode to a non-compressed mode, / RTI &gt; The method of claim &lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; 5. The method of any one of claims 1 to 4, wherein the change in the transmission request includes a change from a compressed mode to a non-compressed mode, the change having a transmission gap, And increasing the transmission quality target value to be applied during the recovery frame. 7. A method according to any one of claims 1 to 6, wherein the transmission quality is represented by a signal-to-interference ratio. 8. A method according to any one of claims 1 to 7, wherein the mobile wireless communication system is a CDMA type of system. 9. A method according to any one of claims 1 to 8, wherein the power control is performed in an uplink transmission direction of the mobile wireless communication system. 10. A method according to any one of claims 1 to 9, wherein the power control is performed in a downlink transmission direction of the mobile wireless communication system. 11. A mobile wireless communication system comprising at least a transmitting entity and a receiving entity for performing the method according to any one of claims 1 to 10, Wherein a first entity of the entities is provided with means for bypassing the reconciliation algorithm and adjusting it in an expected manner by applying the change to the transmission quality target value when a change in the transmission request occurs, system. 12. The apparatus of claim 11, wherein the first entity is means for bypassing the power control algorithm and controlling it in an expected manner by applying a corresponding change to the transmit power when the change in the transmit request occurs The mobile wireless communication system further provided. 13. The mobile wireless communication system according to any one of claims 11 to 12, wherein the first entity is provided with means for determining and / or updating the corresponding change. 14. The system of claim 13, wherein a second one of the entities is provided with means for signaling previous values needed to determine and / or update the corresponding change to the first entity. 15. The mobile wireless communication system according to any one of claims 11 to 14, wherein a second entity of the entities is provided with means for signaling the corresponding change to the first entity. 16. A mobile radio communication system according to any one of claims 11 to 15, wherein a second entity of the entities is provided with means for signaling the occurrence of the change in the transfer request to the first entity. 17. A method according to any one of claims 11 to 16, wherein a second entity of the entities is signaled to the occurrence of the change in the transfer request and means for signaling the change to the first entity Is provided. 18. The mobile wireless communication system according to any one of claims 11 to 17, wherein means for recording the corresponding change is provided to any one of the two entities. 19. The system of any one of claims 11 to 18, wherein one of the two entities is a mobile wireless communications network entity. 20. The mobile wireless communication system according to any one of claims 11 to 19, wherein one of the two entities is a mobile station. A mobile wireless communications network entity, To perform the method according to claim 9 in the uplink transmission direction, And means for bypassing the adjustment algorithm by applying the change to the transmission quality target value and adjusting it in an expected manner when a change in the transmission request occurs. 22. The method of claim 21, And means for bypassing the power control algorithm and controlling it in an expected manner by applying the change to the transmit power if a change in the transmit request occurs. In a mobile station, To perform the method according to claim 10 in the downlink transmission direction, And means for bypassing the adjustment algorithm by applying the change to the transmission quality target value if a change in the transmission request occurs and adjusting it in an expected manner. 24. The method of claim 23, And means for bypassing the power control algorithm by applying the change to the transmit power and controlling it in an expected manner if a change in the transmit request occurs. A mobile wireless communications network entity, To perform the method according to claim 10 in the downlink transmission direction, And means for signaling the change to the mobile station. A mobile wireless communications network entity, To perform the method according to claim 10 in the downlink transmission direction, And means for signaling to the mobile station the occurrence of a change in the transfer request. A mobile wireless communications network entity, To perform the method according to claim 10 in the downlink transmission direction, Means for signaling the occurrence of the change in the transfer request, and means for signaling the change to the mobile station. 28. The method of claim 27, wherein the change in the transfer request comprises a change from a non-compressed mode to a compressed mode and / or a change from a compressed mode to a non-compressed mode, And means for signaling the change. 26. The method of claim 25, wherein the change in the transmission request comprises a change from a non-compressed mode to a compressed mode and / or a change from a compressed mode to a non-compressed mode, And means for signaling the corresponding change component corresponding to the change portion in the transmit request due to the change request. 30. A mobile wireless communications network entity according to claim 28 or 29, wherein said means comprises means for performing said signaling for each compressed frame. 30. A method according to any one of claims 28 to 29, characterized in that if a compressed data unit or frame occurs periodically, the means comprises means for carrying out the signaling once for every compressed frame of a defined period, .